(1) Field of the Invention
This invention relates to the fabrication of integrated circuit devices and more particularly to a method of forming a polysilicon resistor within a contact window.
(2) Description of the Prior Art
The conventional four-transistor static random access memory (SRAM) cell uses a horizontal polysilicon resistor as the load. The resistor is typically one micrometer wide and a couple of micrometers long and occupies space in the RAM cell. As the geometry of RAM cells scales down and memory size increases, there is a need for a resistor of high resistance that does not occupy much space.
U.S. Pat. Nos. 4,965,214 to Choi et al and 4,916,507 to Boudou et al describe methods of achieving particular ranges of resistance values for resistors. U.S. Pat. No. 4,722,913 to Miller describes the doping of a layer of polysilicon by ion implantation only above the source/drain regions to make those locations conductive.